The Receiver Description Including Protocol Specification

Table Navigation Status
Navigation Status
Description
NF
No Fix
DR
Dead reckoning only solution
G2
Stand alone 2D solution
G3
Stand alone 3D solution
D2
Differential 2D solution
D3
Differential 3D solution
RK
Combined GPS + dead reckoning solution
TT
Time only solution
GPS.G6-SW-12013
Public Release
Page 61 of 168

23.3 RATE (PUBX,40)
23.3.1 Set NMEA message output rate
Message
RATE
Description
Set NMEA message output rate
Firmware
Supported on:
• u-blox 6 (GPS/GLONASS/QZSS) firmware version 1.00
Type
Set Message
Comment
Set/Get message rate configuration (s) to/from the receiver.
• Send rate is relative to the event a message is registered on. For example, if the rate of a
navigation message is set to 2, the message is sent every second navigation solution.
ID for CFG-MSG
Number of fields
Message Info
0xF1 0x40
11
Message Structure:
$PUBX,40,msgId,rddc,rus1,rus2,rusb,rspi,reserved*cs
Example:
$PUBX,40,GLL,1,0,0,0,0,0*5D
Field
No.
Name
Unit
Format
Example
Description
0
$PUBX
-
string
$PUBX
Message ID, UBX protocol header, proprietary
sentence
1
ID
-
numeric
40
Proprietary message identifier
2
msgId
-
string
GLL
NMEA message identifier
3
rddc
cycl
es
numeric
1
output rate on DDC
0 disables that message from being output on this
port
1 means that this message is output every epoch
4
rus1
cycl
es
numeric
1
output rate on USART 1
0 disables that message from being output on this
port
1 means that this message is output every epoch
5
rus2
cycl
es
numeric
1
output rate on USART 2
0 disables that message from being output on this
port
1 means that this message is output every epoch
6
rusb
cycl
es
numeric
1
output rate on USB
0 disables that message from being output on this
port
1 means that this message is output every epoch
7
rspi
cycl
es
numeric
1
output rate on SPI
0 disables that message from being output on this
port
1 means that this message is output every epoch
8
reserved
-
numeric
0
Reserved: always fill with 0
9
cs
-
hexadecimal
*5D
Checksum
10

-
character
-
Carriage return and line feed
GPS.G6-SW-12013
Public Release
Page 62 of 168

23.4 SVSTATUS (PUBX,03)
23.4.1 Poll a PUBX,03 message
Message
SVSTATUS
Description
Poll a PUBX,03 message
Firmware
Supported on:
• u-blox 6 (GPS/GLONASS/QZSS) firmware version 1.00
Type
Input Message
Comment
A PUBX,03 message is polled by sending the PUBX,03 message without any data fields.
ID for CFG-MSG
Number of fields
Message Info
0xF1 0x03
4
Message Structure:
$PUBX,03*30
Example:
$PUBX,03*30
Field
No.
Name
Unit
Format
Example
Description
0
$PUBX
-
string
$PUBX
Message ID, UBX protocol header, proprietary
sentence
1
msgId
-
numeric
03
Set to 03 to poll a PUBX,03 message
2
cs
-
hexadecimal
*30
Checksum
3

-
character
-
Carriage return and line feed
23.4.2 Satellite Status
Message
SVSTATUS
Description
Satellite Status
Firmware
Supported on:
• u-blox 6 (GPS/GLONASS/QZSS) firmware version 1.00
Type
Output Message
Comment
The PUBX,03 message contains satellite status information.
ID for CFG-MSG
Number of fields
Message Info
0xF1 0x03
5 + 6*n
Message Structure:
$PUBX,03,GT{,sv,s,az,el,cno,lck},*cs
Example:
$PUBX,03,11,23,-,,,45,010,29,-,,,46,013,07,-,,,42,015,08,U,067,31,42,025,10,U,195,33,46,026,18,U,32
6,08,39,026,17,-,,,32,015,26,U,306,66,48,025,27,U,073,10,36,026,28,U,089,61,46,024,15,-,,,39,014*0D
Field
No.
Name
Unit
Format
Example
Description
0
$PUBX
-
string
$PUBX
Message ID, UBX protocol header, proprietary
sentence
1
msgId
-
numeric
03
Proprietary message identifier: 03
2
n
-
numeric
11
Number of GPS satellites tracked
Start of repeated block (n times)
GPS.G6-SW-12013
Public Release
Page 63 of 168

SVSTATUS continued
Field
No.
Name
Unit
Format
Example
Description
3 +
6*N
sv
-
numeric
23
Satellite ID
4 +
6*N
s
-
character
-
Satellite status, see table below
5 +
6*N
az
deg numeric
-
Satellite azimuth (range: 0-359)
6 +
6*N
el
deg numeric
-
Satellite elevation (range: 0-90)
7 +
6*N
cno
dBH
z
numeric
45
Signal strength (C/N0, range 0-99), blank when not
tracking
8 +
6*N
lck
s
numeric
010
Satellite carrier lock time (range: 0-64)
0:  code lock only
64:  lock for 64 seconds or more
End of repeated block
3 +
6*n
cs
-
hexadecimal
*0D
Checksum
4 +
6*n

-
character
-
Carriage return and line feed
Table Satellite Status
Satellite Status
Description
-
Not used
U
Used in solution
e
Ephemeris available, but not used for navigation
23.5 TIME (PUBX,04)
23.5.1 Poll a PUBX,04 message
Message
TIME
Description
Poll a PUBX,04 message
Firmware
Supported on:
• u-blox 6 (GPS/GLONASS/QZSS) firmware version 1.00
Type
Input Message
Comment
A PUBX,04 message is polled by sending the PUBX,04 message without any data fields.
ID for CFG-MSG
Number of fields
Message Info
0xF1 0x04
4
Message Structure:
$PUBX,04*37
Example:
$PUBX,04*37
Field
No.
Name
Unit
Format
Example
Description
0
$PUBX
-
string
$PUBX
Message ID, UBX protocol header, proprietary
sentence
1
msgId
-
numeric
04
Set to 04 to poll a PUBX,04 message
GPS.G6-SW-12013
Public Release
Page 64 of 168

TIME continued
Field
No.
Name
Unit
Format
Example
Description
2
cs
-
hexadecimal
*37
Checksum
3

-
character
-
Carriage Return and Line Feed
23.5.2 Time of Day and Clock Information
Message
TIME
Description
Time of Day and Clock Information
Firmware
Supported on:
• u-blox 6 (GPS/GLONASS/QZSS) firmware version 1.00
Type
Output Message
Comment
-
ID for CFG-MSG
Number of fields
Message Info
0xF1 0x04
12
Message Structure:
$PUBX,04,time,date,utcTow,utcWk,leapSec,clkBias,clkDrift,tpGran,*cs
Example:
$PUBX,04,073731.00,091202,113851.00,1196,15D,1930035,-2660.664,43,*3C
Field
No.
Name
Unit
Format
Example
Description
0
$PUBX
-
string
$PUBX
Message ID, UBX protocol header, proprietary
sentence
1
msgId
-
numeric
04
Proprietary message identifier: 04
2
time
-
hhmmss.ss
073731.00
UTC time, see 
note on UTC representation
3
date
-
ddmmyy
091202
UTC date, day, month, year format, see 
note on
UTC representation
4
utcTow
s
numeric
113851.00
UTC Time of Week
5
utcWk
-
numeric
1196
UTC week number, continues beyond 1023
6
leapSec
s
numeric/text
15D
Leap seconds
The number is marked with a ‘D’ if the value is the
firmware default value. If the value is not marked it
has been received from a satellite.
7
clkBias
ns
numeric
1930035
Receiver clock bias
8
clkDrift
ns/s numeric
-2660.664
Receiver clock drift
9
tpGran
ns
numeric
43
Time Pulse Granularity, The quantization error of the
TIMEPULSE pin
10
cs
-
hexadecimal
*3C
Checksum
11

-
character
-
Carriage Return and Line Feed
GPS.G6-SW-12013
Public Release
Page 65 of 168

UBX Protocol
24 UBX Protocol Key Features
u-blox GNSS receivers use a u-blox proprietary protocol to transmit GNSS data to a host computer. This
protocol has the following key features:
• Compact - uses 8 Bit Binary Data.
• Checksum Protected - uses a low-overhead checksum algorithm
• Modular - uses a 2-stage message identifier (Class- and Message ID)
25 UBX Packet Structure
A basic UBX Packet looks as follows:
• Every Message starts with 2 Bytes: 0xB5 0x62
• A 1 Byte Class Field follows. The Class defines the basic subset of the message
• A 1 Byte ID Field defines the message that is to follow
• A 2 Byte Length Field is following. Length is defined as being the length of the payload, only. It does not
include Sync Chars, Length Field, Class, ID or CRC fields. The number format of the length field is an
unsigned 16-Bit integer in Little Endian Format.
• The Payload is a variable length field.
• CK_A and CK_B is a 16 Bit checksum whose calculation is defined below.
26 UBX Payload Definition Rules
26.1 Structure Packing
Values are placed in an order that structure packing is not a problem. This means that 2 byte values shall start
on offsets which are a multiple of 2, 4 byte values shall start at a multiple of 4, and so on.
26.2 Message Naming
Referring to messages is done by adding the class name and a dash in front of the message name. For example,
the ECEF-Message is referred to as NAV-POSECEF. Referring to values is done by adding a dash and the name,
e.g. NAV-POSECEF-X
GPS.G6-SW-12013
Public Release
Page 66 of 168

26.3 Number Formats
All multi-byte values are ordered in Little Endian format, unless otherwise indicated.
All floating point values are transmitted in IEEE754 single or double precision. A technical description of the
IEEE754 format can be found in the AnswerBook from the ADS1.x toolkit.
Variable Type Definitions
Short
Type
Size (Bytes)
Comment
Min/Max
Resolution
U1
Unsigned Char
1
0..255
1
I1
Signed Char
1
2's complement
-128..127
1
X1
Bitfield
1
n/a
n/a
U2
Unsigned Short
2
0..65535
1
I2
Signed Short
2
2's complement
-32768..32767
1
X2
Bitfield
2
n/a
n/a
U4
Unsigned Long
4
0..4 '294'967'295 1
I4
Signed Long
4
2's complement
-2'147'483'648 ..
2'147'483'647
1
X4
Bitfield
4
n/a
n/a
R4
IEEE 754 Single Precision
4
-1*2^+127 ..
2^+127
~ Value * 2^-24
R8
IEEE 754 Double Precision
8
-1*2^+1023 ..
2^+1023
~ Value * 2^-53
CH
ASCII / ISO 8859.1 Encoding
1
27 UBX Checksum
The checksum is calculated over the packet, starting and including the CLASS field, up until, but excluding, the
Checksum Field:
The checksum algorithm used is the 8-Bit Fletcher Algorithm, which is used in the TCP standard (
RFC 1145
).
This algorithm works as follows:
Buffer[N] contains the data over which the checksum is to be calculated.
The two CK_ values are 8-Bit unsigned integers, only! If implementing with larger-sized integer values, make
sure to mask both CK_A and CK_B with 0xFF after both operations in the loop.
 CK_A = 0, CK_B = 0
 For(I=0;I {
     CK_A = CK_A + Buffer[I]
     CK_B = CK_B + CK_A
 }
After the loop, the two U1 values contain the checksum, transmitted at the end of the packet.
GPS.G6-SW-12013
Public Release
Page 67 of 168

28 UBX Message Flow
There are certain features associated with the messages being sent back and forth:
28.1 Acknowledgement
When messages from the class CFG are sent to the receiver, the receiver will send an "acknowledge" (
ACK-AC
K
) or a "not acknowledge" (
ACK-NAK
) message back to the sender, depending on whether or not the
message was processed correctly.
Some messages from other classes (e.g. LOG) also use the same acknowledgement mechanism.
28.2 Polling Mechanism
All messages that are output by the receiver in a periodic manner (i.e. messages in classes MON, NAV and
RXM) can also be polled.
There is not a single specific message which polls any other message. The UBX protocol was designed such,
that when sending a message with no payload (or just a single parameter which identifies the poll request) the
message is polled.
29 UBX Class IDs
A class is a grouping of messages which are related to each other. The following table lists all the current
message classes.
Name
Class
Description
NAV
0x01
Navigation Results: Position, Speed, Time, Acc, Heading, DOP, SVs used
RXM
0x02
Receiver Manager Messages: Satellite Status, RTC Status
INF
0x04
Information Messages: Printf-Style Messages, with IDs such as Error, Warning, Notice
ACK
0x05
Ack/Nack Messages: as replies to CFG Input Messages
CFG
0x06
Configuration Input Messages: Set Dynamic Model, Set DOP Mask, Set Baud Rate, etc.
MON
0x0A
Monitoring Messages: Comunication Status, CPU Load, Stack Usage, Task Status
AID
0x0B
AssistNow Aiding Messages: Ephemeris, Almanac, other A-GPS data input
TIM
0x0D
Timing Messages: Time Pulse Output, Timemark Results
All remaining class IDs are reserved.
GPS.G6-SW-12013
Public Release
Page 68 of 168

30 UBX Messages Overview
Page
Mnemonic
Cls/ID
Length
Type
Description
UBX Class ACK
Ack/Nack Messages
72
ACK-ACK
0x05 0x01
2
Output
Message Acknowledged
72
ACK-NAK
0x05 0x00
2
Output
Message Not-Acknowledged
UBX Class AID
AssistNow Aiding Messages
73
AID-ALM
0x0B 0x30
0
Poll Request
Poll GPS Aiding Almanac Data
73
AID-ALM
0x0B 0x30
1
Poll Request
Poll GPS Aiding Almanac Data for a SV
74
AID-ALM
0x0B 0x30
(8) or (40)
Input/Output
GPS Aiding Almanac Input/Output Message
74
AID-ALPSRV
0x0B 0x32
16
Output
ALP client requests AlmanacPlus data from server
75
AID-ALPSRV
0x0B 0x32
16 + 1*dataSize Input
ALP server sends AlmanacPlus data to client
76
AID-ALPSRV
0x0B 0x32
8 + 2*size
Output
ALP client sends AlmanacPlus data to server.
76
AID-ALP
0x0B 0x50
0 + 2*N
Input
ALP file data transfer to the receiver
77
AID-ALP
0x0B 0x50
1
Input
Mark end of data transfer
77
AID-ALP
0x0B 0x50
1
Output
Acknowledges a data transfer
78
AID-ALP
0x0B 0x50
1
Output
Indicate problems with a data transfer
78
AID-ALP
0x0B 0x50
24
Periodic/Polled
Poll the AlmanacPlus status
79
AID-DATA
0x0B 0x10
0
Poll Request
Polls all GPS Initial Aiding Data
79
AID-EPH
0x0B 0x31
0
Poll Request
Poll GPS Aiding Ephemeris Data
79
AID-EPH
0x0B 0x31
1
Poll Request
Poll GPS Aiding Ephemeris Data for a SV
80
AID-EPH
0x0B 0x31
(8) or (104)
Input/Output
GPS Aiding Ephemeris Input/Output Message
81
AID-HUI
0x0B 0x02
0
Poll Request
Poll GPS Health, UTC and ionosphere parameters
81
AID-HUI
0x0B 0x02
72
Input/Output
GPS Health, UTC and ionosphere parameters
82
AID-INI
0x0B 0x01
0
Poll Request
Poll GPS Initial Aiding Data
83
AID-INI
0x0B 0x01
48
Input/Output
Aiding position, time, frequency, clock drift
84
AID-REQ
0x0B 0x00
0
Virtual
Sends a poll (AID-DATA) for all GPS Aiding Data
UBX Class CFG
Configuration Input Messages
85
CFG-ANT
0x06 0x13
0
Poll Request
Poll Antenna Control Settings
85
CFG-ANT
0x06 0x13
4
Input/Output
Antenna Control Settings
86
CFG-CFG
0x06 0x09
(12) or (13)
Command
Clear, Save and Load configurations
88
CFG-DAT
0x06 0x06
0
Poll Request
Poll Datum Setting
88
CFG-DAT
0x06 0x06
44
Input
Set User-defined Datum
89
CFG-DAT
0x06 0x06
52
Output
The currently defined Datum
90
CFG-GNSS
0x06 0x3E
0
Poll Request
Polls the configuration of the GNSS system configuration
90
CFG-GNSS
0x06 0x3E
4 + 8*numConfigBlocks
Input/Output
GNSS system configuration
91
CFG-INF
0x06 0x02
1
Poll Request
Poll INF message configuration for one protocol
92
CFG-INF
0x06 0x02
0 + 10*N
Input/Output
Information message configuration
93
CFG-ITFM
0x06 0x39
0
Poll Request
Polls the Jamming/Interference Monitor configuration.
93
CFG-ITFM
0x06 0x39
8
Command
Jamming/Interference Monitor configuration.
GPS.G6-SW-12013
Public Release
Page 69 of 168

UBX Messages Overview continued
Page
Mnemonic
Cls/ID
Length
Type
Description
94
CFG-MSG
0x06 0x01
2
Poll Request
Poll a message configuration
94
CFG-MSG
0x06 0x01
8
Input/Output
Set Message Rate(s)
95
CFG-MSG
0x06 0x01
3
Input/Output
Set Message Rate
95
CFG-NAV5
0x06 0x24
0
Poll Request
Poll Navigation Engine Settings
96
CFG-NAV5
0x06 0x24
36
Input/Output
Navigation Engine Settings
97
CFG-NAVX5
0x06 0x23
0
Poll Request
Poll Navigation Engine Expert Settings
98
CFG-NAVX5
0x06 0x23
40
Input/Output
Navigation Engine Expert Settings
99
CFG-NMEA
0x06 0x17
0
Poll Request
Poll the NMEA protocol configuration
100
CFG-NMEA
0x06 0x17
4
Input/Output
NMEA protocol configuration (deprecated)
101
CFG-NMEA
0x06 0x17
12
Input/Output
NMEA protocol configuration
103
CFG-NVS
0x06 0x22
13
Command
Clear, Save and Load non-volatile storage data
105
CFG-PM2
0x06 0x3B
0
Poll Request
Poll extended Power Management configuration
105
CFG-PM2
0x06 0x3B
44
Input/Output
Extended Power Management configuration
107
CFG-PRT
0x06 0x00
0
Poll Request
Polls the configuration of the used I/O Port
107
CFG-PRT
0x06 0x00
1
Poll Request
Polls the configuration for one I/O Port
107
CFG-PRT
0x06 0x00
20
Input/Output
Port Configuration for UART
110
CFG-PRT
0x06 0x00
20
Input/Output
Port Configuration for USB Port
111
CFG-PRT
0x06 0x00
20
Input/Output
Port Configuration for SPI Port
114
CFG-PRT
0x06 0x00
20
Input/Output
Port Configuration for DDC Port
116
CFG-RATE
0x06 0x08
0
Poll Request
Poll Navigation/Measurement Rate Settings
116
CFG-RATE
0x06 0x08
6
Input/Output
Navigation/Measurement Rate Settings
117
CFG-RINV
0x06 0x34
0
Poll Request
Poll contents of Remote Inventory
117
CFG-RINV
0x06 0x34
1 + 1*N
Input/Output
Contents of Remote Inventory
118
CFG-RST
0x06 0x04
4
Command
Reset Receiver / Clear Backup Data Structures
119
CFG-RXM
0x06 0x11
0
Poll Request
Poll RXM configuration
119
CFG-RXM
0x06 0x11
2
Input/Output
RXM configuration
120